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Material Development for 3D Printing

by Brittany Willes, contributing editor

Plastics Business

SUBMITTED

In the past few years, injection molders have gone from using 3D printers almost exclusively to create prototypes to exploring larger scale production opportunities for complex parts. However, material developers haven’t always kept up with industry changes.

Plastics Business reached out to injection molders and material suppliers to discuss material development – specifically resin – for the ever expanding world of 3D printing: Mike Idacavage, vice president of business development for Colorado Photopolymer Solutions; Matt Hlavin, president, Thogus Products and its sister company rp+m; and Bob Holbrook, sales and marketing manager, and Ed Graham, engineering manager, ProtoCam. Each was asked for his individual perspectives and experiences regarding material development for 3D printing.

What concerns do plastics molders have about the resin availability for 3D printers, especially as it concerns more precise applications, such as those for the medical industry?

Idacavage: From a liquid resin material supplier perspective, the concerns that I hear from plastic manufacturers can be bucketed into several categories. The first would deal with achieving physical properties that match or exceed current plastic specifications. The second area of concern involves the safety and handling of the resin materials, especially for medical and electronic applications. Once again, this issue seems to be more of a concern for liquid resin suppliers. Finally, the issue of cost does come up. However, compared to the first two concerns, this tends to be a lower priority as the plastics manufacturers are primarily focused on making unique and custom parts that meet target specifications as the highest priority.

Hlavin: From an injection molding standpoint, I do not feel that molders, in general, are overly concerned about resin availability for 3D printers, as the molding community has not implemented additive manufacturing equipment into their business model for production to this point. From my experience, most molders have yet to adopt 3D printing into their businesses. As for the additive industry, materials are one of the most significant factors holding the technology back from becoming a production process.

Graham: Being a former plastic molder, I’ve paid close attention to the inroads being made in resins for 3D printers because we’re now printing a lot of high-heat, chemical-resistant materials. Any application that can now be done with molding, I would say we’re only a few years away from being able to do through 3D printing. For instance, we already have 3D-printed plastics classified as USP Class VI certified materials. When you start heading into that medical sector, there are materials available through 3D printing that meet some of the requirements.

Holbrook: One unique thing coming on the horizon is that it’s not so much the materials themselves but what can be incorporated within the material. For instance, Hewlett-Packard technology is looking at having barcodes printed directly within the part and integrating circuit boards within printed parts, which offers a lot of options you just can’t do with traditional means through injection molding. This could really shake things up, especially when we’re talking about industries like aerospace where there are certification and traceability requirements for parts and products. If we’re able to print a part that is coming off the machine with some type of traceability impregnated within the part itself, that’s pretty impressive.

What differences are there in resin materials developed for 3D printers rather than material developed for traditional injection molding machines?

Idacavage: Speaking as a liquid resin supplier, each resin formulation is fine-tuned for optimum performance in each manufacturer’s 3D printing/additive manufacturing machine. There is enough variation between each brand of 3D printing machine that uses liquid resin to require this customization. While one’s first impression might be that this complicates matters, it also allows each brand of 3D printer to be optimized for the best performance. There are general rules and strategies when developing liquid resin formulations so this is not as daunting a task as it might seem.

Hlavin: Most of the traditional materials developed for 3D printers have been low-end materials specific to prototyping. They have been modified from the production injection molding materials in order to process in these systems. For production to become an output from 3D printers, the materials that have been spec'd into applications like auto, medical (FDA) and aerospace have to be qualified for these machines. The 3D printing companies have not focused on this to date.

Graham: Right now, the 3D printing world is chasing the injection molding world in terms of material development. We’re printing with a lot of Nylon 11 and 12, while the injection molding world is primarily using Nylon 6. Naturally that will be the big push for 3D printing – to get involved and print with Nylon 6. The 3D printed world started out with liquid-based photopolymers – such as epoxy-based or acrylic-based photopolymers – and now we’re getting into more traditional solids that can be made by fused deposition modeling (FDM) or by selective laser sintering (SLS), which are closer to molded products and will have physical properties similar to that of traditional injection molded products.

Holbrook: The 3D printing world is continuing to improve and develop, and it’s really driven by what people want. The demand has been for Nylon 6, so that’s what we’re developing now. We’re already into high-engineered resins, such as polycarbonates and nylons, and that will only continue to grow.

How are resin companies starting to address the needs for 3D printing resins now that 3D printers are not being used simply for prototype creation? (i.e., production requirements)

Idacavage: Initially, the materials provided to 3D printing users were simple modifications to resins that were being used in a variety of other applications. While this worked well for most prototyping applications, it soon became apparent that higher performance resins were needed for new applications. The experience obtained in the early days of 3D printing has propelled development of new resins to meet the requirements of applications other than prototyping. As we gained experience in supplying resins to the early prototyping machines, we developed a much better understanding of the science and technology of exactly how the 3D printers were performing. In addition, our company developed the habit of listening closely to what was being reported in the press and engaging in conversations with printer manufacturers and end users. We are moving past the first-generation resins that worked well initially to higher performance resins that would be practical in day-to-day manufacturing environments.

Hlavin: The material companies that have traditionally focused on injection molding materials have, in part, ignored this space due to the low volumes consumed in 3D printing. They now are waking up to the notion that, in order to win spec, they must have an offering available for 3D printers, which means there is a lot of testing and material formulation work to be done. The material companies also will need to develop support materials, and there are intellectual property considerations that still protect the 3D equipment companies. All those factors must be considered.

Graham: As mentioned earlier, Hewlett-Packard has come out with a new technology, called Jet Fusion, that is going to be able to print almost, or equally, as fast as injection molding using nylons. The company is already developing more resins every day, so we feel that with the launch of this equipment in 2017 more materials are going to come very quickly to add to the nylon capabilities. The industry is developing resins proactively for production vs. for prototype. 3D printing is definitely in the transitional phase right now of moving into production.

Holbrook: On another note, designers are now designing products specifically for additive manufacturing, meaning they wouldn’t be able to be molded in their current configuration. As we move forward, there will be a lot of parts developed and manufactured through the additive process because it will be the only way to do it. With improved design, we’re going to have lighter-weight, stronger and more efficient parts. All of those things play into the additive world.

How are the companies that develop 3D printing equipment assisting with the resin requirements?

Idacavage: We work very closely with equipment manufacturers to understand the limitations and opportunities that each 3D printer brings to the table. Our interaction with the equipment manufacturers ranges from face-to-face meetings to discuss the characteristics of the machines and resins to having one or more commercial machines in our development laboratory. We also receive prototype 3D printers so that the resins would be commercial when the 3D printer is available for sale. In general, it is usually easier to modify the resins than it is to make large changes in the equipment, so the first option would be for us to optimize the resin to achieve the desired properties in the final 3D printed object.

Graham: Right now, we have companies like BASF, a resin manufacturer, working with companies like EOS and other SOS companies. They’re working in tangent with one another, changing the machine parameters to achieve success with higher temperatures and more control. These groups are constantly working together, whether the materials are being developed in-house by the 3D printing OEM or whether there is a sub party on the outside working in tangent with these companies to develop the parameters that are needed. The material suppliers and machine manufacturers have to work together to find out what is needed and how to get there. Not only will it make more materials available more quickly, it will also drive the cost down as well.

Holbrook: We are gearing up for 3D printed production, trying to take the onus off of just being a prototype producer and moving more to that of a production producer. We feel 3D printing will be the next industrial revolution.